High-efficiency multivibrator circuits



c. E. MCCLELLAN 2 ,465,249

Original Filed July 28,1945

March 22, 194-9,

Halalulai Inpu+ Ecurqe Load ' INVENTOR Cyr/i/fM C/eflan.

ATTORN EY WITNESSES: jaw 4 Patented Mar. 22, 1949 UNITED STATS ATENT FFICE HIGH-EFFICIENCY MULTIVIBRATOR CIRCUITS Cyril E. McClellan, Catonsville, Md., assignor to Westinghouse Electric CorporatiomEast Pittsburgh, Pa., a corporationof Pennsylvania 4 Claimst My invention relates to electronic wave generators, and in particular relates to an electronic wave generator of the multivibrator type.

This application is a division of my Patent No. 2,416,188, for High-efi'iciency multivibrator circuits, issued February 18, 1947.

Multivibrator circuits have found an increasing use in the radio art in which current pulses of relatively short duration separated by a longer interval are generated. Such arrangements of the conventional type comprise two electronic tubes, one of which conducts currentonly while the current pulse is flowing, and the other of which conducts current. during the longer in terval between pulses. The current flow in the latter tube is thus very nearly continuous and represents a continued loss of power which may be hundreds of times greater than the power put into the useful pulses. Hence such an arrangement is, in reality, highly inefficient from an electrical power standpoint.

The objects of my invention are to provide an arrangement for using electronic tubes to generate pulses of substantially the above-described type and which comprises two tubes, but in which both tubes are extinguished except during the relatively short time of the current pulse.

Another object of. my invention is to provide an arrangement in which current through the tubes between the anodes and cathodes is limited only by the electron emission of the cathode itself.

Another object of my invention is to provide a multivibrator in which tubes of a given current and voltage rating permit a much larger useful output of power than is the case with conventional multivibrators of the prior art.

A still further object of my invention is to provide an electronic pulse generator which permits a greatly increased elliciency and large saving of power wasted in conventional multivibrators now known.

Other objects of my invention will become apparent upon reading the following description taken in connection with the drawing in which the single figure is a diagrammatic showing of a circuit embodying the principles of my invention.

Referring particularly to the drawing, a grid controlled electronic tube I has its anode connected directly to the positive terminal 3 of a direct current source of which the negative terminal is grounded. A second electronic gridcontrolled tube 2 has its anode connected through a resistor 4 to the terminal 3. The

cathode of the tube I is connected to ground through a resistor 5 while the cathode of the tube 2v is connected to ground through the primary winding 6,-a resistor l, and a secondary winding 13 of a transformer or double-winding transmission choke coil of the same type as has already been described in my Patent 2,379,168, issued June 26, 1945. The common terminal of the winding 5 and the resistor I is connected through a capacitor 9 to the control electrode of the tube l, and also to the control electrode of the tube 2. The control electrodes of the tubes i and 2 are connected through a resistor 2i to the terminal l2 of a source of bias potential of which the other terminal is grounded. The control electrode of the tube 2 is connected through a capacitor 14 with one terminal of a source of input voltage of which the other terminal is grounded.

The tubes l and 2 are biased by a source 42 to such a potential that they are both nonconducting when no current flows through the resistors 5 and i. If, now a positive pulse of signal voltage is impressed on the control electrode of tube 2 through the capacitor l4, current fiow occurs. between the anode and cathode. of tube 2 from the source 3, passing through resistor 4. The current flowing from the cathode of tube 2 through windings 6 and B and resistor 1 acts through capacitor 9 to impress a positive voltage pulse on the control electrodes of both tubes l and 2, thereby tending to render both of them more freely conductive to current between their principal electrodes. As is pointedout between lines 49 and '73 of the first column on page 2 ofthe printed copy of my abovementioned patent, the polarity of the windings t and 8 is such that voltage drop in the cathode resistor 5 induces an electromotive force in the winding 8 which is impressed upon the control electrodes of the tubes i and 2, making them more positive and counteracting the currentlimiting effect of the voltage drop in said cathode resistor. Current flow in these tubes accordingly rapidly rises to the saturation value characteristicv of the electron-emission of their cathodes. When: the current flow from the tube 2 through resistor reaches this steady state, the capacitor 9 begins to discharge through resistor 2| and source 12, and thereby decreases the potential on the control electrodes of the tubes l and 2. In consequence, current flow in these tubes begins to decrease; the voltage drop across the resistors l and 5 begins to decrease, and the condenser 9 then begins to impress an increasingly negative voltage on the control electrodes of the tubes I and 2. This negative voltage acts to further and more rapidly decrease the flow of current through these tubes from the source 3 and quickly causes the cutoff of all current flow through them if the positive voltage pulse is no longer impressed on the control electrode of the tube 2 through capacitor 14. The tubes l and 2 are accordingly extinguished and current flow remains cut off until another positive signal pulse is impressed on the control electrode of tube 2 through capacitor 14.

While I have described one specific embodiment of the principles of my invention, they are of broader application in ways which will be evident to those skilled in the art.

I claim as my invention:

1. An impulse generator comprising a first grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of a direct current voltage source and its cathode connected to the negative terminal of said source through an impedance, a second grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of said source through an impedance and its cathode connected to one end of a primary winding the other end of which is connected to the first-mentioned cathode through another impedance, a secondary winding closely coupled to said primary winding and connected to shunt the first mentioned impedance, a capacitor connected between the terminal of said other impedance which is closest to the cathode of said second electron tube and a common connection to the control electrodes of said electronic tubes, a source of bias potential connected to impress voltage through a resistor on the control electrodes of said electron tubes, and means for impressing an input voltage on the control electrode of at least one of said tubes.

2. An impulse generator comprising a first grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of a direct current voltage source and its cathode connected to the negative terminal of said source through an impedance, a second grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of said source through an impedance and its cathode connected to one end of a primary winding the other end of which is connected to the first-mentioned cathode through another impedance, a secondary winding closely coupled to said primary winding and connected to shunt the first mentioned impedance, the polarity of said windings being such that current flowing from the cathode of the second-mentioned tube to the negative terminal of said source will produce opposing magnetic effects in said windings, a capacitor connected between the terminal of said other impedance which is closest to the cathode of said second electron tube and a conunon connection to the control electrodes of said electronic tubes, a source of bias potential connected to impress voltage through a resistor on the control electrodes of said electron tubes, and means for impressing an input voltage on the control electrode of at least one of said tubes.

3. An impulse generator comprising a first grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of a direct current voltage source and its cathode connected to the negative terminal of said source through a resistor, a second grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of said source through a second resistor and its cathode connected to one end of a primary winding the other end of which is connected to the first-mentioned cathode through a third resistor, a secondary winding closely coupled to said primary winding and connected to shunt the first mentioned resistor, a capacitor connected between the terminal of said third resistor which is closest to the cathode of said second electron tube and a common connection to the control electrodes of said electronic tubes, a source of bias potential connected to impress voltage through a fourth resistor on the control electrodes of said electron tubes, and means for impressing an input voltage on the control electrode of at least one of said tubes.

4. An impulse generator comprising a first grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of a direct current voltage source and its cathode connected to the negative terminal of said source through a resistor, a second grid controlled electron tube having an anode and a cathode and having its anode connected to the positive terminal of said source through a second resistor and its cathode connected to one end of a primary winding the other end of which is connected to the first-mentioned cathode through a third resistor, a secondary winding closely coupled to said primary winding and connected to shunt the first mentioned resistor, the polarity of said windings being such that current flowing from the cathode of the second-mentioned tube to the negative terminal of said source will produce opposing magnetic effects in said windings, a capacitor connected between the terminal of said third resistor which is closest to the cathode of said second electron tube and a common connection to the control electrodes of said electronic tubes, a source of bias potential connected to impress voltage through a fourth resistor on the control electrodes of said electron tubes, and means for impressing an input voltage on the control electrode of at least one of said tubes.

CYRIL E. McCLELLAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,266,668 Tubbs Dec. 16, 1941 2,275,016 Koch Mar. 3, 1942 2,305,930 Martinelli Dec. 22, 1942 

